In a conventional finishing apparatus having a circular vibratory finishing tub, the finishing operations are performemd with the tub open at the top to facilitate a visual inspection of the flowing mass. However, this causes the disadvantage of limiting the volume of workpieces which can be finished, causing damage or defects to the workpieces due to the impact thereof with each other, the media and the tub under strong vibration and reducing the mass separating efficiency due to the backflow of the mass.
There are conventional finishing apparatuses having a circular vibratory finishing tub, a rotary barrel or mill, a centrifugal barrel, or a vibratory finishing tub or box type in which the barrel or the like is closed in operation. However, all of those apparatuses provide only a means of closing the barrel or the like without which it would be impossible to operate the apparatus since the contents would otherwise be easily vibrated out, or a means of closing the barrel or the like to prevent water from the finishing compound from spattering out. In other words, this is simply a covering means, but not a means of finishing workpieces effectively by vibration under a heavily compressed condition as in this invention.